100 Billion Alien Planets in Milky Way Galaxy, Says Study

A new study claims there could be at least 100 billion planets in our galaxy, furthering the chances that life could inhabit one of these so-called exo-planets.

Lead author Jonathan Swift, of Caltech in Pasadena, was able to make his prediction after studying a distant, 5-planet solar system called Kepler-32 which is roughly 915 light-years from Earth.

Researchers were able to discover the orbiting planets using NASA's Kepler Space Telescope, which is able to detect the dimness in light caused when an exo-planet passes in front of a star. The five planets that were discovered were said to orbit an M dwarf, a star that is smaller than, but not as hot as, our sun.

Researchers also said that M dwarfs are the most common type of star in our galaxy, comprising nearly 75 percent of the Milky Way's estimated 100 billion stars. Using a mathematical formula that takes the number of these types of stars and the estimated number of exo-planets orbiting such celestial bodies, researchers were able to determine that as many as 100 billion planets could be present in our galaxy.

"It's a staggering number, if you think about it … basically there's one of these planets per star," Swift said in a statement.

The results were published soon after other scientists predicted that an "alien Earth" would be found in 2013.

There has been a concerted effort over the last decade aimed at finding a planet outside our solar system that orbit a star in what's known as the habitable zone – the distance a plant must be from a star in order to support life.

Scientists have logged several of these celestial bodies, known as exo-planets, during the past decade. What has intrigued astronomers thus far is discovering that a few of these exo-planets share one or two traits similar to Earth. These traits relate to the size of the Earth as well as the surface temperature that is known to be hospitable to life as we know it.

"I'm very positive that the first Earth twin will be discovered next year," Abel Mendez, of the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo, told Space.com.